FastVLM WebGPU

Overview

FastVLM WebGPU is a privacy-focused web application that brings AI-powered video captioning directly to your browser. Using the lightweight FastVLM-0.5B model, it analyzes video frames from your webcam or uploaded videos and generates descriptive captions in real-time—all without sending any data to external servers.

Features

• Dual Video Input: Support for both live webcam feeds and uploaded video files
• Real-time Captioning: Continuous frame analysis with streaming text output
• 100% Private: All processing happens locally in your browser—no data leaves your device
• Modern UI: Elegant glass-morphism design with draggable components
• Custom Prompts: Personalize captions with your own instructions
• Full Video Controls: Play, pause, seek, and volume control for uploaded videos
• Offline Capable: Works completely offline after initial model download
• GPU Accelerated: Leverages WebGPU for fast, efficient inference
• Accessible: Built with ARIA labels and semantic HTML

Technologies

• React 19 with TypeScript for type-safe UI development
• WebGPU for GPU-accelerated model inference
• @huggingface/transformers for running ML models in the browser
• Tailwind CSS 4 for modern, responsive styling
• Vite 7 for lightning-fast development and optimized builds
• ONNX Runtime with quantized model weights (Q4) for efficient inference

Getting Started

Prerequisites

• Node.js 18+ or Bun runtime
• A modern browser with WebGPU support (Chrome 113+, Edge 113+, or Opera 99+)

Installation

# Clone the repository
git clone <your-repo-url>
cd fastvlm-webgpu

# Install dependencies (using Bun)
bun install

# Or using npm
npm install

Development

# Start the development server
bun dev

# Or using npm
npm run dev

Open http://localhost:5173 in your browser.

Building for Production

# Build the project
bun run build

# Preview the production build
bun run preview

Usage

1. Choose Your Video Source: Select either webcam or upload a video file
2. Grant Permissions: Allow webcam access if using live video
3. Wait for Model Loading: The FastVLM model will download and initialize (first time only)
4. Start Captioning: Click "Start Captioning" to begin real-time analysis
5. Customize Prompts: Enter custom instructions in the prompt box to guide the AI
6. View Live Captions: Watch as captions stream in real-time based on the video content

How It Works

FastVLM WebGPU uses a lightweight Vision Language Model (FastVLM-0.5B) optimized for browser inference:

1. Frame Capture: Extracts frames from video at 50ms intervals using HTML5 Canvas API
2. Vision Encoding: Processes frames through the vision encoder (Q4 quantized)
3. Language Generation: Generates captions using the decoder with custom prompts
4. Streaming Output: Displays tokens as they are generated for real-time feedback

The entire pipeline runs client-side using WebGPU for hardware acceleration, ensuring privacy and enabling offline usage.

Model Details

• Model: FastVLM-0.5B (ONNX format)
• Parameters: 500 million
• Quantization: 4-bit (Q4) for decoder and vision encoder, fp16 for embeddings
• Max Tokens: 512 tokens per inference
• Format: ONNX Runtime Web with WebGPU backend

Browser Compatibility

• Chrome 113+ - Supported
• Edge 113+ - Supported
• Opera 99+ - Supported
• Firefox - WebGPU in development
• Safari - WebGPU in development

Project Structure

fastvlm-webgpu/
├── src/
│   ├── components/         # React UI components
│   │   ├── CaptioningView.tsx
│   │   ├── PromptInput.tsx
│   │   ├── LiveCaption.tsx
│   │   └── ...
│   ├── context/           # VLM model context and hooks
│   │   └── VLMContext.tsx
│   ├── types/             # TypeScript type definitions
│   ├── constants/         # App constants and configurations
│   └── App.tsx            # Root application component
├── package.json
├── vite.config.ts
└── tsconfig.json

Credits

This project is an improved version of the original FastVLM WebGPU demo by Apple, with enhancements including:

• Enhanced UI/UX with glass-morphism design
• Draggable interface components
• Support for both webcam and file upload
• Improved prompt management with suggestions
• Better error handling and loading states
• Full video playback controls
• Accessibility improvements

Acknowledgments

• Original FastVLM WebGPU implementation by Apple
• Hugging Face Transformers.js team for the browser ML framework
• FastVLM model researchers and contributors